Composite filaments having an elastic crimping property

ABSTRACT

Composite filament having an elastic crimping property, comprised of at least two components disposed in an eccentric sheath-core relation along the longitudinal axis of the filament, in which one component is composed of a polyester consisting mainly of polyethylene terephthalate and another component or components comprise highly shrinkable polyamide having a shrinking percentage of 15-80 percent and the percent by weight of the core or cores in the filament is 5-50. It is preferable that the core component is composed of the polyester and the sheath component is composed of the polyamide. Furthermore, the eccentricity of the sheath-core relation is preferably at least 5. The core component may be constituted with a plurality number of cores.

United States Patent Ogata et al. Feb. 15, 1972 [54] COMPOSITE FILAMENTSHAVING AN 2,932,079 4/1960 Dietzsch et al. ..161/ 175 ELASTIC CRIMPINGPROPERTY 5,983,397 651361 Breen 161/173 ,03 35 6 1 62 Zimmerman 161/175[721 lnvenmm Osaka; TSII- 3,459,846 8/1969 Matsui et al. ...264/17l iz fg g g f fi 3,488,251 6/1970 Etchells et al. ..161/l77 ira au, o apan 731Assignees: Kanegaluchi Boseki Kabushiki Kaisha, FOREIGN PATENTS ORAPPLICATIONS Tokyo, Japan; SNlA Vismsa Societa 43/ 16671 7/1968 Japan.....264/D|G. 26 Nazionale lndustria pplicazioni Viscosa 43/22350 9/1968.Japan ..l6l/l75 S.p.A., Milan, Italy Primary Examiner-William J. VanBalen [22] Flled' 1969 AssistantExaminer-Raymond O. Linker, Jr. [21]Appl. No.: 807,863 Attorney-Stevens, Davis, Miller & Mosher 30 ForeignApplication Priority Data [57] ABSTRACT Composite filament having anelastic crimping property, comr japan ,prised of at least two componentsdisposed in an eccentric 1968 Japan "43/25756 sheath-core relation alongthe longitudinal axis of the filaapan ment, in which one component iscomposed of a polyester consisting mainly of polyethylene terephthalateand another [52] US. Cl ..l6l/l73, 161/175, 11/ 1 7 1, component orcomponents comprise highly Shrinkable po]ya [51 1 Int Cl D01 d 5/28 midehaving a shrinking percentage of 15-80 percent and the 58] Fieid 264/168percent by weight of the core or cores in the filament is 5-50. a 2 DIGIt is preferable that the core component is composed of the polyesterand the sheath component is composed of the polyamide. Furthermore, theeccentricity of the sheath-core rela- [56] References Cited tion ispreferably at least 5. The core component may be con- UNITED STATESPATENTS stituted with a plurality number of cores. 3,540,080 1 l/ 1970Goossens ..l8/8 18 Claims, 15 Drawing Figures Pmmmrmsmz 3.642.565

' SHEET 2 or 2 Fig. /0 Fig. Fig. I?

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ATTORNEYS COMPOSITE FILAMENTS HAVING AN ELASTIC CRIMPING PROPERTY Thepresent invention relates to novel synthetic filaments, particularly tocomposite filaments having a high crimpability, an improved crimpelasticity and an excellent dyeability.

lt has heretofore been well known that when different synthetic linearpolymers are melted and conjugate spun simultaneously through commonorifices in a sheath-core relation along the axial direction of theunitary filament, and the resulting filaments are drawn and subjected toshrinking treatment, then composite filaments having three-dimensionalspiral crimps can be obtained.

Recently, a number of proposals have been made with respect to compositefilaments having such three-dimensional crimp developability. Forexample, it has been known that as two polymer components constitutingcomposite filaments, different homopolyamides, a homopolyamide and acopolyamide, different homopolyesters and a homopolyester and acopolyester are used in view of mutual adhesivity, conjugatespinnability and drawability, and the two polymers are bonded in aside-by-side relation as shown in FIG. 1, and composite filaments havinga crimp developability are manufactured by the use of the differencebetween the shrinkabilities of both the polymers.

However, in these filaments, it is very difficult to improve propertiesother than crimping property, because two kinds of polymers constitutingthe composite filament have very similar chemical and physicalproperties.

.That is, the polyamide composite filament has poor crimp elasticity,resilient crimpability and crimp bulkiness. While, the polyestercomposite filament has excellent crimp elasticity, but has insufficientcrimp durability because of its poor recovering properties forelongation, bending and compression.

Furthermore, polyamide-polyester composite filaments are known, whereina homopolyester component is arranged in the core portion and ahomopolyamide component is arranged in the sheath portion eccentricallyto the core portion in order to compensate mutually the above-mentioneddrawbacks in the polyamide composite filament and the polyestercomposite filament.

However, even when such composite filaments are subjected to a crimpdeveloping treatment to develop threedimensional crimps, it is difficultto develop desired crimps, because the difference of shrinkabilitybetween the homopolyester component and the homopolyamide componentconstituting the composite filament is small, and they are arranged in asheath-core relation. Moreover, when the sheath-core-type compositefilaments of polyamide-polyester obtained by a conventional conjugatespinning process are subjected to a shrinking treatment to developcrimps, the ex cellent crimp elasticity of the polyester componentcannot be developed fully on the whole filament, because the polyestercomponent having elastic property is arranged in the inside portion ofthe crimps. Moreover, as the polyester component having poor recoveringproperty for elongation is arranged in the inside portion of the crimps,the composite filament does not easily recover the original state, afterapplied mechanical stresses, such as repeating elongations, bendings,compressions, etc. Therefore, a desirable crimp durability cannot beobtained in the conventional sheath-core-type composite filament ofpolyamide-polyester.

Furthermore, conventional composite filaments have only latentcrimpability and do not develop spontaneous crimps even if the conjugatespun filaments are relaxed after drawing and they are linear as in usualmonofilament and develop three-dimensional crimps only after they aresubjected to shrinking treatments, such as hot water treatment and dryheat treatment. Furthermore, when the composite filaments having theabove-mentioned latent crimpability are knitted or woven into textures,such as stockings, socks, tricots and carpets, and then the resultingtextures are directly subjected to a crimp developing treatment, tensionand contact interference between mutual filaments in the texturesuppress the crimp developability considerably and develop considerablynonuniform crimps to form unevenness on the surface of the texture. Inorder to obviate such disadvantages in the crimp developing treatmentafter knitting or weaving, drawn composite filaments are generallysubjected to a pretreatment, by which the drawn composite filaments aretwisted or passed through a particular heater under tensionless state todevelop preliminary crimps, and then led to various knitting or weavingsteps.

It has been now surprisingly found that by obeying to novel criticalcombination components and their nature, of physical characteristics ofsuch components and of certain new relationship thereof in the structureof the composite filament, novel and useful composite filaments havinglatent crimpability and solved conventional various drawbacks completelycan be obtained.

The object of the present invention is to provide a sheathcore-typecomposite filament of polyamide-polyester having a high crimpdevelopability, which has never been attained in the conventionalsheath-core-type composite filament, by using a highly shrinkablepolyamide as the polyamide component to make a difference of shrinkingpercentage between the polyamide component and the polyester componentlarger, and further selecting the conjugate ratio of the polyestercomponent and the degree of the eccentricity of core componentcorresponding to the shrinking percentage of the polyamide component.

Another object of the present invention is to provide a compositefilament having an excellent crimp elasticity and crimp recoveringproperty, even when the filament is applied to mechanical stresses, suchas repeating elongations, compressions and bendings, in said compositefilament,,a polyamide component having an excellent recovering propertyfor elongation being located in the inside portion of the crimps and ahighly elastic polyester component being located in the out side portionof the crimps, when the composite filament is subjected to a shrinkingtreatment to develop crimps.

Further object of the invention is to provide a composite filamenthaving an excellent spontaneous crimpability which has never been seenin the conventional filament, that is, a novel composite filamentcapable of developing crimps spontaneously only by relaxing the drawnfilament.

Other objects of the invention will be more apparent from the followingdescription.

That is, the present invention provides a composite filament having anelastic crimping property. Wherein at least two different syntheticlinear polymers are bonded in a sheath-core relation along thelongitudinal direction of the unitary filament, characterized in thatone polymer component is composed of a polyester consisting mainly ofpolyethylene terephthalate and another polymer component is composed ofa highly shrinkable polyamide having a shrinking percentage in boilingwater of at least l5 percent, that both the polymer components arearranged eccentrically in the cross section of the unitary filament, andthat the core component occupies 1050 percent by weight in the unitaryfilament.

It is necessary that the above-mentioned polyamide to be used in thepresent invention has a shrinking percentage in boiling water of l580percent, preferably at least 20 percent. When the shrinking percentageis less than 15 percent, a satisfactory crimp is formed with difficultyand the shrinking percentage is preferable to be higher, but when theshrinking percentage is more than percent, the commercial productioncannot be effected.

The shrinking percentage is determined by the following manner.

The spun and drawn filaments are dipped in boiling water at C. for 15minutes under a load of 0.5 mg./d. and are shrunk. The shrinkingpercentage is shown by the percentage of apparent loss of the lengthcalculated by the following formula:

lit- 1 Shrinking percentage= X 100 wherein l designates the length ofthe shrunk filament and 1,, the length of the original filament.

Generally speaking, ordinary homopolyamides have a shrinking percentagein boiling water of less than l percent, but high molecular weighthomopolyamides having an intrinsic viscosity [n] of more than 1.15 inm-cresol at 30 C. have a shrinking percentage in boiling water of morethan percent, and can be used in the present invention.

The most preferable highly shrinkable polyamides are copolyamide. Thatis, when the minor component of copolymerization in the copolyamidefilament consisting of at least two polyamide-forming components is atleast 5 percent by weight, the shrinking percentage in boiling waterofthe filament reaches usually more than percent. While, when the majorcomponent of copolymerization is more than 95 percent by weight, it ispreferable to increase the molecular weight of the copolyamide as in thecase of the above-mentioned homopolyamides, otherwise in many cases theusual molecular weight of such copolyamides show the similar lowshrinking percentage to conventional homopolyamides, such aspolycaproamide or polyhexamethylene adipamide previously used and havingan ordinary viscosityv Therefore, the difference of shrinking percentagein boiling water between the copolyamide component and the polyestercomponent (usually 10-13 percent) is not sufficient, and it is difficultto obtain composite filaments having a desired crimpability.Furthermore, it is not preferable that for the purpose of increasing thedifference of the shrinking percentage in boiling water between thecopolyamide component and the polyester component, the amount of theminor component in the comonomers constituting the copolyamide componentis extremely increased. Because, the melting point, crystallinity, heatresistance, strength, initial modulus, etc., of the copolyamidedecrease. In general, the amount of polyamide-forming minor component inthe copolyamide should adopt such a value that the difference of theshrinking percentage from the polyester component is increased to theabove necessary extent, within the range of at most percent by weight,preferably at most 20 percent by weight.

For a better understanding of the invention, reference is taken to theaccompanying drawings, wherein FIG. I is a cross sectional view, in anenlarged scale, of a conventional side-by-side-type composite filament,

FIG. 2 is a cross-sectional view, in an enlarged scale, of aconventional concentric sheath-core-type composite filament,

FIG. 3 is a cross-sectional view, in an enlarged scale, of a monocoreeccentric sheath-core-type composite filament according to theinvention,

FIG. 4 is a cross-sectional view, in an enlarged scale, of an eccentricsheath-core-type composite filament according to the invention, whereintwo separate cores are embedded eccentrically in the sheath,

FIG. 5 is a cross-sectional view, in an enlarged scale, of an eccentricsheath-core-type composite filament according to the invention, whereinfour cores are embedded eccentrically in the sheath,

FIG. 6 is a cross-sectional view, in an enlarged scale, of asheath-core-type composite filament according to the invention, whereina core having a noncircular cross section is disposed eccentrically inthe sheath,

FIGS. 7 and 8 are cross-sectional views, in an enlarged scale, ofsheath-core-type composite filaments according to the invention, whereinat least two cores having a noncircular cross section are disposedeccentrically in the sheath, and

FIGS. 9-15 are cross-sectional views, in an enlarged scale, ofembodiments of composite filaments according to the invention, which arecomposed of three different components.

The present invention provides sheath-core-type composite filamentsarranged highly shrinkable polyamide not used in the past and polyestereccentrically in the cross section of the unitary filament. Suchcomposite filaments, when merely relaxed after spinning and drawing,develop spontaneous crimps, the inside portion of which is located bythe polyamide component having a high recovering property forelongation. Moreover, when the composite filaments having theabovementioned spontaneous crimps are subjected to a shrinkingtreatment, latent crimps are further developed remarkably along thecrimp direction of the spontaneous crimps. Furthermore, in thesefilaments, the polyamide component having an excellent recoveringproperty for elongation locates in the inside portion of the crimps andthe polyester component having a high modulus of elasticity locates inthe outside portion of the crimps, and consequently composite filamentshaving a high crimpability, improved crimp durability and crimpelasticity, which have never been obtained, can be easily obtained.

In order to attain the object of the present invention, it is preferableto select the degree of eccentricity of the core component dependingupon the shrinking percentage ofthe polyamide component to be used so asto satisfy the following formulae:

as; (1.4a 50b+ 200%) X 10*;10 :11; 15 and 10c50 wherein 0 represents ashrinking percentage of the polyamide component, b represents percentageof eccentricity of the center of gravity (P) of core componentpositioned in the cross section of the unitary filament against theradius of the unitary filament, and c represents percent by weight ofthe core component in the unitary filament, at the same time.

In the above formulae, the percentage of eccentricity b shows a measureof the degree of eccentricity of the core portion and is shown in thefollowing way.

When the distance between the center (0) of the filament and the centerof gravity (P) of the core component is OP in the unitary filament, andthe radius of said unitary filament is r, then the percentage ofeccentricity b is shown by the ratio of OP/r.

The percentage of eccentricity is preferably at least 5.

In the composite filament shown in FIG. 2, the percentage ofeccentricity b is 0 In the composite filaments of the present invention,the number of cores in the cross section of the unitary filament is notalways one, but may be plural as shown in FIGS. 4 and 5. In the filamentshown in FIG. 4, the center of gravity (P) of the core components liesat the center of the straight line connecting the centers of gravity P1and P2 of respective cores. In the filament shown in FIG. 5, the centerof gravity (P) can be determined in the same manner. The cross-sectionalshape of the core component is not always circular, but may benoncircular as shown in FIGS. 68.

In the present invention, the amount occupied by the core component inthe unitary filament is l050 percent by weight, preferably 20-40percent. When the amount is less than l0 percent by weight, it isdifficult to obtain a composite filament having a desired crimpabilityand crimp elasticity. While, when the amount is more than 50 percent byweight, the percentage ofeccentricity of the core component in the crosssection of unitary filament is too small, and it is difficult to obtaina highly crimpable composite filament.

The composite filament according to the invention is particularlyuseful, when the shrinking percentage 0 of the polyamide component to beused, the percentage of eccentricity b of the core component and thepercent by weight c ofthe core component in the unitary filament satisfythe relation shown by the above-mentioned formulae.

The most useful composite filament in the present invention is multicorefilaments, in which the core component locating in the cross section ofthe filament consists of two or more cores composed ofa polyester andthe sheath component consists ofa highly shrinkable polyamide, andfurther the abovementioned formulae l and the following formulas (2)E201 and 821.1 (2) mean of diameters of ratio of initial modulus andratio of heat shrinkability of the polyamide based on the polyesterrespectively, are satisfied at the same time.

In the above-mentioned formulas (2), N(D/R) represents a ratio (byweight) of the core component based on bonded total component.Furthermore, if theinitial moduli and heatshrinkabilities of thepolyester and the polyamide are expressed by Ee, En, and Se, Sn,respectively, the ratio of initial modulus and the ratio ofheat-shrinkability in the formulas (2) are shown by E=En/Ee and S=Sn/Se.For example, when the polyamide used has a low initial modulus, theratio E of initial modulus of the polyamide based on the polyester isless than and even if such composite filament is subjected to a crimpdeveloping treatment, the crimp recovering property and crimp elasticityof the developed crimps are not satisfactory. While, in the case of theratio of heat-shrinkability S being less than 1.1, even if the drawnfilament is relaxed, the spontaneous crimpability is poor, and furtherthe curliness after a crimp developing treatment is extremely low.Therefore, composite filaments having such a low crimpability are notsuitable for the present invention.

Another preferable composite filament capable of attaining the object ofthe present invention is one, wherein the highly shrinkable polyamidecomponent composing the filament a homopolyamide component and acopolyamide component which form distinct filamentary components and arebonded along the filament axis, and further a core composed of apolyester component is embedded in said homopolyamide component withoutcontacting with the above-mentioned copolyamide component.

That is, such a composite filament is characterized in that said corecomponent is composed of a polyester consisting mainly of polyethyleneterephthalate, and said sheath component is composed of at least twohighly shrinkable polyamide components, a homopolyamide component havingsubstantially homogeneous composition and a copolyamide component beingarranged eccentrically in the cross section of the unitary filament,that said polyester component occupies l0-50 percent by weight in theunitary filament, and that said polyester component locates in saidhomopolyamide component without contacting with said copolyamidecomponent said polyester component with the center of the filament andthe other of which connects the center of gravity of said copolyamidecomponent with the center ofthe filament, in the cross section of theunitary filament, is between 90 and 180.

The bonding configuration of the above-mentioned three components, i.e.,copolyamide, homopolyamide and polyester in the cross section of thecomposite filament of the present invention is shown, for example, byFIGS. 9-15, and the fundamental bonding configuration is shown by FIGS.9 and 10.

That is, in the filament shown in FIG. 9, the copolyamide component(hereinafter referred to as component B) and the polyester component(hereinafter referred to as component C') are arranged in the coreportion, and the homopolyamide component (hereinafter referred to ascomponent A") is arranged in the sheath portion, and three components A,B and C are arranged eccentrically to each other. Furthermore, in FIG.10, the component A and the component B are arranged in a side-by-siderelation and the component C is arranged eccentrically to the componentB as a core. The feature of the present invention lies in that thecomponent C is surrounded by the component A in both the filaments shownin FlGS. 9 and 10. However, when the component C is surrounded by thecomponent B, a composite filament having an excellent crimpabilitycannot be obtained. That is, when such a composite filament is subjectedto a crimp developing treatment, the composite filament develops crimps,in which the polyester component locates in the inside portion of crimpsas in the case of conventional polyesterpolyamide core-sheath compositefilaments. Consequently, the contribution of the modulus of elasticityof the polyester component to the total crimps is small, and further asthe polyester component having poor recovering property for elongationlocates in the inside portion of the crimps, such a filament isinsufiicient in the crimp recovering properties and crimp durabilitiesfor mechanical stresses, such as repeating elongations, bendings andcompressions.

The most important characteristics of the present invention lie in thatthe polyester component is arranged in a defined relation against thepolyamide component. This defined arrangement will be explained withreference to drawings.

As shown in FIG. 11, it is necessary that the copolyamide and P 0 (theangle is hereinafter referred to as eccentric angle), one of whichconnects the center of gravity P, of the copolyamide component with thecenter 0 of the filament and the other of which connects the center ofgravity P of the polyester component with the center 0 of the filament,is between and The bonding configurations shown in FIGS. 9 and 10 havean eccentric angle 0f0z=l80.

FIG. 12 shows an embodiment, wherein the polyester component forms onecore and the copolyamide component forms two cores. The center ofgravity (P) of the copolyamide component lies at the center of thestraight lines P7 connecting respective centers of gravity P and P Whenthe eccentric angle a is exceeds the above-mentioned range, that is, a 590 the copolyamide component and the polyester component are too closelyarranged, and it is difficult to attain the object of the invention. Thecross-sectional configurations of the above-mentioned three componentsand the unitary filament of the composite filament of the presentinvention may be noncircular as shown in FlGS. 1 -15.

When the above-mentioned highly shrinkable polyamide components arecomposed of two components of a homopolyamide component and a at least20-80 percent by weight, preferably 30-80 percent by weight, and theamount of the above-mentioned component is within the range of 8-70percent by weight preferably 10-50 percent by weight. When thehomopolyamide component is less than 20 percent by weight, or the amountof the copolyamide component is percent by weight, the area occupied bythe large, and various disadvantages owing to the use of copolyamideoccur, and particularly, initial modulus, heat resistance and lightresistance decrease. While, when the amount of the homopolyamidecomponent is more than 80 percent by weight, the amount of thecopolyamide component reduces considerably, and a composite filamenthaving a desired crimpability cannot be obtained.

The composite filament according to the present invention can be spun bymeans of conventional spinning process and apparatus.

Furthermore, the drawing can be effected without the use of specialprocess and apparatus, and effected by means of the exactly same processand apparatus as conventionally used. For example, cold drawing at roomtemperature or hot drawing by means of a hot drawn pin or hot drawrollers heated at 60-1 80 C. can be used.

includes copolyesters of main component of polyethylene terephthalatewith other polyesters, such as polyethylene isophthalate,polytetramethylene terephthalate, polyethylene oxybenzoate, polyethylenehexahydroterephthalate, etc. However, in the above-mentionedcopolyester, the

amount of minor component of the copolymerization is preferably lessthan percent by weight, and when the amount of such minor componentexceeds 5 percent by weight, the melting point, crystallinity and yarnproperty, particularly original length ofthe filament in the drawnstate.

2. Total curliness:

The bundle of 30 drawn filaments having a length of 30 cm. is dipped inboiling water for 10 minutes under a load of 0.1

modulus of elasticity reduce due to the copolymerization and 5 mg./d.and then air-dried under the same load. The total curlifurther thecrimpability decreases owing to the increase of after rimp de elopingtreatment is Shown by the perheat-shrinkability. centage of apparentloss ofthe length calculated by the follow- As the homopolyamidecomponent having substantially g equationlo la homogeneous compositionto be used in the present invention, Total curliness= 0 X 100 mentionmay be made of homopolyamides obtained by 10 polymerizing cycliclactams, such as caprolactam, enantholacwherein designates the length ofthe crimped filament and tam, lauryllactam and the like, or nylon saltsof diamines, such l the original length ofthe filament in the drawnstate. as tetramethylenediamine, hexamethylenediamine, un- 3. Crimpelasticity: decamethylenediamine, m-xylylenediamine, pxy- The crimpelasticity is shown by the load (mg./d.) required lylenediamine,bis-(p-aminocyclohexyl)methane and the like, is for stretching thelength of the crimped composite filament with dicarboxylic acids, suchas adipic acid, sebacic acid, bundle obtained in paragraph (2)(underaload of0.l mg./d.) dodecanedicarboxylic acid, isophthalic acid,hexto I percent. ahydroterephthalic acid and the like. Furthermore, asthe Crimp recovering percentage for elongation: highly shrinkablecopolyamide component, mention may be h length of the filament, when thecrimped composite made of copolyamides obtained by copolymerizing atleast 20 filament bundle in the above paragraph(2) is appliedaload oftwo conventional polyamide-forming components including .2 mg./d., is 1an the g when a load of g-Idis the above-mentioned cyclic lactams andnylon salts, further added fOi one minute, i5 1 and then the length, 2

The composite filament according to the present invention in after r e hload f -l g-/ 15. has a merit that when the filament is unwound from abobbin C i recovering percentage f elongation and relaxed, it developsuniform spontaneous crimps having a 1 o spiral three-dimensionalstructure which have never been X 100 developed in the conventionalcomposite filament. Furtherli l more, when such spontaneously crimpedfilament is subjected imp r overing percentage for compression; toshrinking treatments, such as swelling, wetting and heating, The crimpedcomposite filaments Obtained n the above latent crimps are added inaddition to the spontaneous crimps P g p are Cut into a length w 20 ofwhich are and extremely high crimps are formed. Therefore, when theintroduced into a measuring cyiihdei' having a diameter of 5 compositefilaments according to the invention are made into -v and a Piston of200 weight moiihis the crimped various knitted goods, woven fabrics andpile articles, even if composite filaments and thereafter Said measuringcyiihder is the filaments obtained by conjugate spinning and drawing aresiibleFted t a fine vibrtftioii and the eqtiiiihiihm Position ofdirectly subjected to a knitting step or a weaving step without thePiston is read height 0)- pretreatment, which is necessary for theconventional filafi iofici of 9 is further l P to Said Piston andmerits, crimped products having an extremely excellent qualitheequiiihiiiiihlioshioh of the Piston is read in the Same ty and peculiarproperties can be obtained. Moreover, when ih'fihher as described aboveheight is Thei'eaiiteiy the composite filament is subjected to a crimpdeveloping 40 Stiid iofid of 600 iS removed y t Position of thetreatment the mamem develops crimps, in which the piston IS recoverednaturally and after 5 mmutes the height is polyester component having anexcellent elastic property read (the height 1 locates in the outsideportion and the polyamide component The crimp recovering percentage forcqmpression having an excellent recovering property for elongationlocates L, l0 in the inside portion, and therefore a crimped filamenthaving =FOX 100 an excellent crimp elasticity and crimp recoveringproperty A, and further having a high bulkiness, stretchability anddura- Dyeabiiityi bility similar to those ofwool can b b i d into a dyebath prepared by dissolving 0.03 g. of acid dye, The composite filamentaccording to the invention can be Cooihassif Uiita Sky SE (manufacturedy it in used in a wide field not only for garments but also forindustri- 50 F- waist is PP i Of diawh iiiaiheht and of g al materialsand interior ornaments in the form of continuous ciai acetic acid isadded iheiieio- The, the assehihiy is heated mamems or Staple flb fromroom temperature to 95 C. in 30 minutes and main- The invention will beexplained in more detail with talned at the same temperature for 30minutes. The percentreference to lhe following exumples age of dyeabsorped shows the dyeability Crimping properties and dyeability shownin the following EXAMPLE I examples are determined as follows.

i. Spontaneous curliness: Polyethylene terephthalate having an intrinsicviscosity [n] The bundle of 30 drawn filaments having a length of 30 cm.of 0.63 in o-chlorophenol at 30 C. and polycaproamideis applied to aload of 0.1 mg./d. The spontaneous curliness is polyhexamethyleneisophthalamide copolymer (hereinafter shown by the percentage ofapparent loss of the length calcuabridged as 6/61) with a predeterminedcopolymerization ratio lated by the following equation. having anintrinsic viscosity [n] of l.02 in m-cresol at 30 C. were melted andconjugate spun at a temperature of 285 C. in Spontaneous curl1ness= X10D an eccentric sheath-core relation, in which polyethyleneterephthalate formed a core and 6/6l copolymer formed a wherein Idesignates the length of the spontaneously 5 sheath, in a conjugateratio (by weight) of 1:3 by means ofa crimped filament under the load of0.l mg ld. and 1 the conventional conjugate spinning apparatus, and thenthe TABLE 1 Shrinking Copolymeripercentage zation ratio of mono- Elouga-Initial of 6/61 filament Stre th tion modulus Sample No. (by weight)Kind of composite filament (percent) (g. d.) (percent) (g./d.) 100/0Conventional composite filament 12 4.8 82 35 99/1 Composite filamentbeyond the scope of the present invention 13 4.8 31 36 95/5 Compositefilament oi the present invention 23 4. 7 34 34 90/10 d0 34 4.7 30 3580/20 ...(10 50 4.4 35 31 /26 Composite filament beyond the scope of thepresent invention. 62 3.8 38 25 resulting filaments wcrc cold drawn 3.7times their original length at room temperature to obtain drawncomposite filaments of 70 d./l 8 f.

An enlarged cross section of this filament had a bonding configurationas shown in FIG. 3, in which an eccentricity b of polyethyleneterephthalate of the core portion was 50 percent.

Yarn qualities of the composite filaments are shown in Table 1.

Furthermore, the results of crimp property measured with respect to theabove-described composite filaments are shown 10 in Table 2.

h: yeability (percent) a Crimp Crimp recovering recovering percen epercent e for elonfor com gation pression D (percent) (percent) TABLE 2Crimp Crimp l recovering recovering Sponts- Crimp percentage percentageneous Total elas-- for elonfor comcurllness curllness tlclty, gatlonpresslon CHIDD elasticity (percent) (percent) mg./d. (percent) (percent)after king eatment (percent) Total curliness Initial shrin modulus trConcerning the above-described crimped filaments Nos. l6, the positionof polyethylene terephthalate of the core component in the cross sectionof the filament was checked by means of a polarizing microscope, and asthe result polyethylene terephthalate in Nos. 1 and 2 located in theinside portion of the crimp, while the polyester in Nos. 3 to 6 locatedin the outside ofthe crimp. Filaments Nos. 1 and 2 did not developspontaneous crimps, when they were drawn and relaxed, but filaments Nos.3 to 5 developed spontaneous crimps when they were drawn and relaxed incrimped filaments thereof the total curliness was large, and the crimpelasticity and crimp recovering percentage were excellent. Filament No.6 was poor in the yarn quality as shown in Table l and therefore hadpoor crimp elasticity and crimp recover- 4O ing properties, even thoughsuch a filament developed spontaneous crimps and had an excellent totalcurliness.

TABLE 3 Weight percentage of polyethylene Yarn quality terephthalate inmono- Elonfilament Stre th gation I (percent) (57d) (percent) 4. on 4.4. 4. 4.

EXAMPLE 2 The same polyethylene terephthalate as used in Example 1 andpolyhexamethylene adipamide-polycaproamide copolymer having an intrinsicviscosity [n] of H3 in m-cresol at 30 C. (copolymerization ratio of66/6=90/l0) were melted and conjugate spun at a temperature of 285 C. ina predetermined conjugate ratio as shown in Table 3 by means ofaconventional sheath-core-type conjugate spinning apparatus, and then theresulting filaments were drawn 3.9 times their original length on a drawpin heated at 80 C. to obtain drawn composite filaments of 70 d./l 8 f.

The obtained composite filament had a bonding configuration as shown inFIG. 7, in which two elliptical polyester core components existed in theeccentricity of 30 percent.

On the other hand, copolyamide constituting the sheath portion of thecomposite filament was spun solely and the shrinking percentage of theresulting filament was measured and was 30 percent.

Yarn quality and crimp property of each composite filament i are shownin Table 3.

As seen from Table 3, in the filament No. 8 having a small content ofpolyethylene terephthalate (polyester component), a satisfactory crimpproperty was not obtained. On the contra- 5 ry, in the filaments Nos. 9and 10, the content of the polyester E beyond thab""""""""' 9665i beyondthe scope of the invention Kind of composite filament Composite filament[or control Composite filament Com osite fil component was within thescope of the present invention and all formulas to be applied to thepresent invention were satisfied, so that these filaments showed anexcellent crimp property. In the filament No. ll, the content of thepolyester component was larger than that of polyamide component, so thatthe dyeability for an acid dyestuff considerably lowered and such afilament was not used practically.

TABLE 4 Crimp Crimp recovering recovering Sponpercentage percentageEccentaneous Total Crimp for elonfor com- Sample triclty curlinesscurliness elasticity gation pression No. Kind of composite filament(percent) (percent) (percent) (mg/ti.) (percent) (percent) opo oi theinvention 7.1 60 invention 21 67 10. 7 79 7 EXAMPLE 3 means of the conugate spinning apparatus of Example I, and

then the resulting filaments were drawn 4.2 times their original lengthon a draw pin heated at 90 C. to obtain drawn composite filaments of 70d./l 8 f. respectively.

Enlarged cross sections of these composite filaments had respectivelybonding configurations as shown in FIG. 3, in which the eccentricity bof the polyamide component of the core portion was 50 percent.

Crimp properties of the composite filaments thus obtained are shown inTable 6.

Concerning the crimped filaments Nos. 17 to after shrunk, the positionof the polyamide component in the cross 25 section was checked by meansof a polarizing microscope. In

The same polyethylene terephthalate as used in Example 1 and acopolyamide having an intrinsic viscosity [n] of 1.08 in l m-cresol atC. which was obtained by reacting caprolactam with a salt ofN,N-bis(y-aminopropyl) piperazine and adipic acid in a weight ratio of92/8, were conjugate spun in a sheath-core relation in whichpolyethylene terephthalate was a core component and copolyamide was asheath component, at a temperature of 285 C. by means of the apparatusused in Example 1 in a conjugate ratio (by weight) of 30:70. In thiscase, the eccentricity of polyethylene terephthalate arranged in a formof circle in the core portion was changed variously.

the resultmg filaments were drawn times their the filaments Nos. 17, 18,20 and 21,the polyamide located in original length at room temperatureto obtain drawn comthe outside portion f the crimp Th f the polyester Pmonofilamems of component having poor recovering property for elongationFurthermorei the abov? descnbed copolyamlde Spun located mainly in theinside portion of the crimp, so that the solely and drawn to obtain acontrol filament, the shrinking 3O crimp recovering property ftelongation or compression Percenmge Ofwhlch was P was poor. On the otherhand, in the composite filaments Nos.

Crimp Properties of obtained composite filaments are 19 and 22-25 of thepresent invention containing high Show" in Table I shrinkable polyamidcin the core portion, the polyamidc comf"? from Table the filaments 13havmg an ponent located in the inside of the crimp, so that the crimpeccentricity preferable for the present invention were ex- 35 recoveringproperty was considerably high and crimpability tremely superior incrimpability, crimp elasticity and crimp was good recovering propertiesto the filament No. 12.

EXAMPLE 5 EXAMPLE 4 Polyethylene terephthalate having an intrinsicviscosity of The same polyethylene terephthalate as used in Example I0.65 in o-chlorophenol at 30 C. and nylon-6 having an intrinand threekinds of polyamides having various intrinsic viscosisic viscosity of1.15 in m-cresol at 30 C. were melted and conties as shown in thefollowing Table 5 were melted and conjujugate spun in an eccentricsheath-core relation, in which the gate spun in such a sheath-corerelation that the polyester polyethylene terephthalate formed the coreand the nylon-6 component was arranged in the sheath portion and thepolyaformed the sheath, at a temperature of 285 C., the ratio midecomponent was arranged in the core portion, at a tem- N(D/R) of the corecomponent to the total bonded comperature of 285 C. in a conjugate ratio(by weight) of 3:1 by ponents being 0.05, 0.10, 0.25, 0.40 and 0.5, andthen the resulting filaments were cold drawn 3.79 times their originallength to obtain drawn composite filaments of 70 d./l8 f., which had across section as shown in FIG. 4. in this case, the

Shrinking percentage of difference between heat shrinking percentages inboth com TABLE 6 m ponents was 50 percent, i.e., S=l .5.

$3212; 5 32: Strength, elongation, dyeability and crimp property afterPolyemide [1;] (percent) treatment for developing crimps in the obtainedcomposite A 0.95 11.3 filaments are shown in Table 7. D 3 13,1 As seenfrom Table 7, when N(D/R) is less 0. l0 within the g- 6-5? :g-i scope ofthe present invention, the obtained composite fila- E. 1108 14:2 ment isextremely low in the curliness after developed crimps. g: d :32 Further,as seen from the spontaneous curliness in Table 7, the H d 1.08 28.6particularly preferable two-core composite filament according to thepresent invention develops crimps immediately when it TABLE 6 CrimpCrimp recovering recovering Spontapercentage percentage neous TotalCrimp for elongafor com- I curliness curliness elasticity tion pressionKind of composite filament (percent) (percent) (mg./d.) (percent)(percent) Conventional composite filament 1 21 11 'I o 4 29 13 10Composite filament of the present inventio 18 43 16. 6 48 36 Compositefilament beyond the scope of the i 2 16 12 d0 13 31 12.9 21 18 Conpositefilament of the present invention 0 do TABLE 8 Crimp re- Sponta- Totalcovering per- Eccenneous curlcurliness Crimp eentage for Sample tricangle iness (percent) elasticity elongation No. a Kind of compositefilament (percent) (0.1 mg./d.) (mg/d (percent) 70 Composite filamentbeyond the scope of the invention. 0. 6 21. 4 0.8 58

100 Composite filament of the invention. 13. 3 45. 6 1. 4 74 TABLE 10Total Crimp Conjugate Spontacurliness recovering ratio Copolymerineous(percent) Crimp percentage (by weight) zation ratio curliness (0.1elasticity for elongation Sample No. A :B:C oi 66/610 Kind of compositefilament (percent) mg./d.) (mg./d.) (percent) 45 50:50:0 100/0 11.2 46"50:50:0 97/3 25. 6 0.1 58 47 50:50:0 95/5 38. 4 0.3 61 48 50 50:0 00/1057.1 0. 5 63 40 50 :50:0 80/20 70. 2 0.9 00 50 35:50:15 100/0 24. 7 0.556 51 35:50: 97/3 20. 6 0.0 67 52 65:50:15 05/5 42. 9 2. 5 70 5335:50:15 00/10 67.8 3. 0 82 54 35:50:15 80/20 17. 6 80.8 5. 5 87 isdrawn and relaxed and such a filament shows crimp property afterdeveloped crimps.

Moreover, the parts showing no numerical value in NS( D/R l+E) of Table7 do not satisfy the range ofthe formula (2) according to the presentinvention.

an excellent EXAMPLE 6 Polyethylene terephthalate (C-component) havingan intrinsic viscosity [n] of 0.65 in o-chlorophenol at 30 C.,p0lycaprolactam-polyhexamethylene adipamide copolymer (copolymerizationcomposition of 6/66=80/20 weight ratio, B-component) having an intrinsicviscosity [n] of l.05 in mcresol at 30 C. and polycaprolactam(A-component) having an intrinsic viscosity [n] of 1.0 in m-cresol at 30C. were melted and conjugate spun in an eccentric sheath-core relation,wherein the B-component and the C-component formed the cores and theA-component formed sheath, in a conjugate ratio (by weight)ofA.-B.-C=80: l0: 10 at a temperature of 280 C. by means of aconventional conjugate spinning apparatus, and then the resultingfilaments were cold drawn 3.8 times their original length to obtaindrawn composite filaments of 70 d./l8 f.

An enlarged cross section of this filament had a bonding configurationas shown in FIG. 11, in which an eccentric angle a between theB-component and the C-component of core portions were changed variously.

Crimp properties of the composite filaments having said variouseccentric angles were measured and the results are shown in Table 8.

Concerning the crimped filaments Nos. 3538, the position of theC-component, polyester in the cross section of the filament was checkedby a polarizing microscope, and as the result the polyester in thefilament No. 35 located in the inside of the crimp, while the polyesterin the filaments Nos. 36-38 located in the outside of the crimp.Accordingly, in the filament No. 35 the spontaneous crimp was somewhatpoor, the total curliness after a shrinking treatment was considerablylow, and the crimp elasticity and recovering percentage for elongationwere poor. On the contrary, in the crimpdeveloped composite filamentsNos. 36-38 according to the present invention, the total curliness aftera shrinking treatment was particularly high and the crimp elasticity andrecovering percentage for elongation were excellent.

EXAMPLE 7 Polyethylene terephthalate (C-component) and polycaprolactam(A-component) used in Example 6, and polycaprolactampolyhexamethyleneisophthalamide copolymer (copolymerization composition of 6/6l=85/l5weight ratio, B- component) having an intrinsic viscosity [n] of l.l3 inmcresol at 30 ture of 280 C. in a predetermined conjugate ratio as shownin Table 9 by means of a conventional sheath-core-type conjugatespinning apparatus, and then the resulting filaments were drawn 3.9times their original length on a draw pin heated at C. to obtain drawncomposite filaments of 70 d./l 8 f.

The obtained composite filament had a bonding configuration as shown inFIG. 13, in which the B-component and the C-component were semicircularcores, and the eccentric angle a was Yarn quality, crimp property anddyeability of each composite filament are shown in Table 9.

As seen from Table 9, in the filaments Nos. 41 to 44 containing morethan 10 percent of polyester component (C-component) with highelasticity, splendid spiral spontaneous crimps were developed when theywere drawn and relaxed, and when these drawn filaments were subjected toa shrinking treatment, a tension due to a contact interference betweenmutual filaments by the spontaneous crimp was small, so that theextremely excellent crimps were developed, and particularly crimpdevelopability under a high load was excellent.

Furthermore, in the composite filaments Nos. 41-43 of the presentinvention, it was found that crimp elasticity and recovery forelongation were excellent. In the filament No. 44 containing 60 percentof polyester component (C-component), crimp property was fairly good,but had a fault in point of dyeability for acid dye.

EXAMPLE 8 Polyhexamethylene adipamide (A-component) having an intrinsicviscosity [n] of 1.02 in m-cresol at 30 C., polyhexamethyleneadipamide-polyhexamethylene sebacamide copolymer (66/610, B-component)having an intrinsic viscosity [n] of l.l2 and polyethylene terephthalateused in Example 6 (C-component) were melted and conjugate spun in aconjugate ratio (by weight) of A:B:C=35:50: l 5: at a temperature of 290C. by means of a conventional conjugate spinning apparatus forthree-component system, and then the resulting filaments were hot drawn4.l times their original length on a draw pin heated at 70 C. to obtaindrawn composite monofilaments of 15 deniers.

The obtained composite monofilament had a bonding configuration as shownin FIG. 10, in which C-component was arranged as a core component inA-component, A-component and B-component were bonded in a side-by-siderelation, and an eccentric angle a between B- and C-components was 180.

For a comparison, the above described A- and B-components were conjugatespun in a conjugate ratio (by weight) of lzl by means ofa conventionalside-by-side-type conjugate spinning apparatus for two component systemwithout using polyester of C-component and drawn under the same condi-C. were melted and conjugate spun at a temperations as described aboveto obtain drawn composite monofilament of 15 deniers having a bondingconfiguration as shown in FIG. 1.

Crimp properties of said composite filaments are shown in Table 10.

As seen from Table 10, conventional polyamide series composite filamentsNos. 45-49 did not develop spontaneous crimp at all and developed spirallatent crimps for the first time by a shrinking treatment. On the otherhand, in the filaments Nos. 52-54 of the present invention containinghigh shrinkable copolyamide, spontaneous crimps were developed when suchfilaments were drawn and relaxed, and further the more excellent crimpswere developed by a shrinking treatment, and also crimp elasticity andrecovery for elongation were more excellent as compared with those ofthe conventional polyamide series composite filaments. In the filamentNo. 51, the shrinking percentage of B-component was not so high, so thatthe crimp property was poor as in the case of the filament No. 50.

What is claimed is:

1. A composite filament having elastic crimping property, comprising atleast two components disposed in an eccentric sheath-core relation alongthe longitudinal axis of the filament, wherein a. the first component isthe core component composed of a polyester consisting essentially ofpolyethylene terephthalate; and

b. the second and any other components comprise the sheath of a highlyshrinkable polyamide having a shrinking percentage of 15-85 percent; thepercent by weight ofcore component in the filament being 5-50; and thefollowing conditions (1) and (2) being present at the same time: (I) (i)3.8 (l.4a X 5017+ 200 and (ii) B Z 5;

wherein a represents said shrinking percentage of the sheath component,

b represents the percentage of eccentricity of the center of gravity (P)of the core component positioned in the cross section of the filamentagainst the radius of the filament,

and

represents said percentage of the core component; and (2) (i) 1.2 X 1ONS(D/R) (l +1?) 5 10.1 X (NE 2);

(ii)E 5 0.1;and (iii) S e 1.1; wherein D is the arithmetic mean ofdiameters of each core, when the cores are circular, or when the coresare noncircular, is the arithmetic mean of diameters of circles, whensaid noncircular cores are calculated into circles, R is the diameter ofthe filament, N is the number ofcores, E is the ratio of initial modulusof the polyamide to the polyester, and S is the ratio of heatshrinkability of the polyamide to the polyester. 2. The compositefilament as claimed in claim 1, wherein said shrinking percentage is atleast percent.

3. The composite filament as claimed in claim 1, wherein said percent byweight of the core or cores in the filament is 20 4. The compositefilament as claimed in claim 1 which has at least two cores.

5. The composite filament as claimed in claim 1, wherein said polyamideis a homopolyamide having an intrinsic viscosity ofat least 1.15.

6. The composite filament as claimed in claim 1, wherein saidhomopolyamide is nylon-6 or nylon-66.

7. The composite filament as claimed in claim 1, wherein said polyamideis a copolyamide of more than 95 percent by weight ofa polyamide-formingconstituent and less than 5 percent by weight of anotherpolyamide-forming constituent and having an intrinsic viscosity of atleast 1.15.

8. The composite filament as claimed in claim 1, wherein said polyamideis a copolyamide of 95 70 percent by weight of a polyamide-formingconstituent and 5 30 percent by weight of another polyamide-formingconstituent.

9. The composite filament as claimed in claim 1, wherein said polyamideis of poly(caproamide/hexamethylene adipamide),poly(caproamide/hexamethylene isophthalamide) or poly(hexamethyleneadipamide/hexamethyl'ene sebacamide).

10. The composite filament as claimed in claim 1, wherein the sheath isconstituted with two polyamide components disposed eccentrically to eachother in distinct zone with intimate adherent surface extending alongthe filament axis, one of said components consists of a homopolyamide,the other of said components consists of a copolyamide and further thecore composed of said polyester component is embedded in saidhomopolyamide component without contacting with said copolyamidecomponent.

11, The composite filament as claimed in claim 10, wherein the core andthe copolyamide component of the sheath are arranged under such acondition that the lesser angle a formed by two straight lines, one ofwhich connects the center of gravity of said core with the center of thefilament and the other of which connects the center of gravity of saidcopolyamide component with the center of filament, in the cross sectionof the filament, is the range between and 180.

12. The composite filament as claimed in claim 10, wherein the shrinkingpercentage of the copolyamide component is at least 3 percent higherthan that of the homopolyamide component.

13. The composite filament as claimed in claim 10, wherein saidcopolyamide consists of less than percent by weight of apolyamide-forming constituent and more than 5 percent by weight ofanother polyamide-forming constituent.

14. The composite filament as claimed in claim 10, wherein saidhomopolyamide component is of nylon-6 or nylon-66.

15. The composite filament as claimed in claim 10, wherein saidcopolyamide component is of poly(caproamide/hexamethylene adipamide),poly(caproamide/hexamethylene isophthalamide) or poly(hexamethyleneadipamide/hexamethylene sebacamide).

16. The composite filament as claimed in claim 10, wherein saidhomopolyamide and said copolyamide are arranged in a side-by-siderelation.

17. The composite filament as claimed in claim 10, wherein saidhomopolyamide and said copolyamide are arranged in an eccentricsheath-core relation.

18. The composite filament of claim 1, wherein polyethyleneterephthalate comprises at least 95 percent of said first component (a).

2. The composite filament as claimed in claim 1, wherein said shrinkingpercentage is at least 20 percent.
 3. The composite filament as claimedin claim 1, wherein said percent by weight of the core or cores in thefilament is 20 *40.
 4. The composite filament as claimed in claim 1which has at least two cores.
 5. The composite filament as claimed inclaim 1, wherein said polyamide is a homopolyamide having an intrinsicviscosity of at least 1.15.
 6. The composite filament as claimed inclaim 1, wherein said homopolyamide is nylon-6 or nylon-66.
 7. Thecomposite filament as claimed in claim 1, wherein said polyamide is acopolyamide of more than 95 percent by weight of a polyamide-formingconstituent and less than 5 percent by weight of anotherpolyamide-forming constituent and having an intrinsic viscosity of atleast 1.15.
 8. The composite filament as claimed in claim 1, whereinsaid polyamide is a copolyamide of 95 *70 percent by weight of apolyamide-forming constituent and 5 *30 percent by weight of anotherpolyamide-forming constituent.
 9. The composite filament as claimed inclaim 1, wherein said polyamide is of poly(caproamide/hexamethyleneadipamide), poly(caproamide/hexamethylene isophthalamide) orpoly(hexamethylene adipamide/hexamethylene sebacamide).
 10. Thecomposite filament as claimed in claim 1, wherein the sheath isconstituted with two polyamide components disposed eccentrically to eachother in distinct zone with intimate adherent surface extending alongthe filament axis, one of said components consists of a homopolyamide,the other of said components consists of a copolyamide and further thecore composed of said polyester component is embedded in saidhomopolyamide component without contacting with said copolyamidecomponent.
 11. The composite filament as claimed in claim 10, whereinthe core and the copolyamide component of the sheath are arranged undersuch a condition that the lesser angle Alpha formed by two straightlines, one of which connects the center of gravity of said core with thecenter of the filament and the other of which connects the center ofgravity of said copolyamide component with the center of filament, inthe cross section of the filament, is the range between 90* and 180*.12. The composite filament as claimed in claim 10, wherein the shrinkingpercentage of the copolyamide component is at least 3 percent higherthan that of the homopolyamide component.
 13. The composite filament asclaimed in claim 10, wherein said copolyamide consists of less than 95percent by weight of a polyamide-forming constituent and more than 5percent by weight of another polyamide-forming constituent.
 14. Thecomposite filament as claimed in claim 10, wherein said homopolyamidecomponent is of nylon-6 or nylon-66.
 15. The composite filament asclaimed in claim 10, wherein said copolyamide component is ofpoly(caproamide/hexamethylene adipamide), poly(caproamide/hexamethyleneisophthalamide) or poly(hexamethylene adipamide/hexamethylenesebacamide).
 16. The composite filament as claimed in claim 10, whereinsaid homopolyamide and said copolyamide are arranged in a side-by-siderelation.
 17. The composite filament as claimed in claim 10, whereinsaid homopolyamide and said copolyamide are arranged in an eccentricsheath-core relation.
 18. The composite filament of claim 1, whereinpolyethylene terephthalate comprises at least 95 percent of said firstcomponent (a).